This objective of this proposal is to test the feasibility of a new breathe feedback system, the Patient Compliance Breath Feedback System, for improving patient compliance to drug therapies. This system incorporates aromatic compounds into a medication which are then detected by an array of chemoselective biosensors that measures the presence of the aromatic marker compound in the breath of a patient. Positive results of this study could lead to the integration of the system with a phone callback system for monitoring drug schedules in homebound patients.